A significant trend throughout integrated circuit (IC) development is the downsizing of IC components. As the size reduces, the performance requirements become more stringent. Also, as devices continue to shrink in size, the channel region continues to shrink as well. For metal-oxide-semiconductor field effect transistors (MOSFETs), increased performance requirements have generally been met by aggressively scaling the length of the channel region. However, such a short channel length faces high electric field and manufacturing limits.
As the length of a channel continues to shrink, diffusion of dopants becomes much harder to control. There are various thermal processes throughout a semiconductor manufacturing. For example, after dopants are implanted into a substrate, a thermal process is used to activate the dopants. However, these thermal processes cause dopant diffusion in an unintentional way. In addition, shorter channel lengths suffer from fluctuation of higher implantation concentration and depth. As the dopant concentration reaches about 1E20 atoms/cm3, the dopants will easily diffuse into channel regions and induce short channel effects during a thermal process. The electrical properties, such as threshold voltage, are altered and deviated from a predetermined value. This causes uniformity between each device and is a severe problem in circuit design. As such, a sufficient method to control the doped profile is required.